The scratch was first reported by GloboEsporte.com, and MMAjunkie.com (www.mmajunkie.com) has since confirmed the change with multiple sources close to the promotion.

GloboEsporte.com’s report cited a herniated disc as the reason for the withdrawal. A timetable for his return was not immediately established.

Rua and Nogueira had been looking to renew a rivalry that began in 2005 when the two faced off in the quarterfinal round of PRIDE’s middleweight grand prix.

In a fight that many news media outlets dubbed fight of the year, Rua earned a hard-fought unanimous decision victory. Rua went on to win the star-studded and historic 16-man tournament a few months later.

The two fighters have seen mixed results in recent years. Rua has alternated between wins and losses during his past eight fights, which included a brief UFC title run from 2010-2011 and a December defeat to Alexander Gustafsson. Nogueira, meanwhile, recently halted a two-fight losing skid with back-to-back wins over Tito Ortiz and Evans.

Nogueira’s withdrawal is the second high-profile hit the the UFC 161 lineup. The card was originally expected to feature a bantamweight interim title fight between interim champ Renan Barao and former WEC titleholder Eddie Wineland. However, the Brazilian champ was forced to withdraw from the card, and the night’s co-feature between Rashad Evans and Dan Henderson was promoted to headlining status.

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